The present invention relates to an angular adjustment mechanism for controlling linear movement along a first axis and rotary means disposed along a second axis angularly disposed to and intersecting the first axis, preferably at substantially a right angle, for actuating relatively light loads such as automobile headlight assemblies or the like. More particularly, the invention relates to an improved assembly and construction of such mechanisms when utilized for tilting headlight assemblies to bring about a change in the direction of the light beam.
As the design of headlights for vehicles, such as automobiles, has evolved, the headlights have adapted their exterior configuration to either be hidden by tiltable flaps which, when the lights are enclosed, serve to smooth the surrounding car surfaces to improve the aerodynamics of the front end of the car during non-use of the headlights. Other forms of headlights have been designed to have their lenses smoothly follow the contour of the grill and hood and to provide an aerodynamically efficient headlamp design. However, it is still necessary that means be provided to permit adjustment of the light beam to a predetermined direction so as to improve the safety of the vehicle in traffic by preventing unnecessary glare of the headlamp being directed toward oncoming vehicles.
Where the aerodynamic design of the vehicles is of paramount concern, it has been found that prior art adjusting means, which required access to adjusting means from the forward exterior of the vehicles, was not acceptable. Removal of trim to gain access to the adjusting means requiring specialized tools was unacceptable since the owner of the vehicle could not readily make the necessary adjustment without the assistance of a professional mechanic. Similarly, the utilization of openings to provide access to adjustment means through the grill or the hood resulted in undesirable whistling when confronted with the wind, as well as providing passages for accumulation of dirt and debris which clog up the access to the adjustment means.
Thus, such aerodynamically efficient headlamp designs have lead to modular designs requiring the headlamp adjusting mechanism to be located within the interior of the engine compartment so that the adjusting mechanism is easily accessible, whereby, headlamp realignment or adjustment would not require removal of any exterior bezels or trim and could be done expeditiously from the interior of the engine compartment. Examples of such interiorly accessible devices can be found in U.S. Pat. No. 4,737,891 to Burton (the same inventor and assignee as the present invention); U.S. Pat. No. 4,893,219 to Lisak; and U.S. Pat. No. 4,916,587 to Hirose et. al.
The patents to Lisak '219 and Hirose et. al. '587 disclose two forms of gear means for translating the rotary motion of a drive gear to the linear motion of the adjusting means acting on the headlamp assembly. More specifically, Hirose et. al. use a motor 77 with spur gears 80, 83 forming a reducing gear train driving the worm 81 which in turn drives the gear 86 causing ultimate linear motion in the adjusting means 47. Finite adjustment can be accomplished through a second gear set 21 and drive rod 42. A complex, detailed mechanism of great cost. On the other hand, the Lisak invention utilizes a plurality of parts including a so-called one-piece housing 22 having intersecting bores and recesses 24 and 26 with closure caps 38-39 that accommodate gears 32 and 34, in the recesses, with the latter gear 34 being assembled to and carried on nut member 34a while the former gear 32 is positioned on drive shaft 40 by the metallic retainer or springrip 42 which retains the shaft 40 totally within the recess 24 by acting on one of two caps, namely 39 and 38. The assembly of shaft 40 is a blind operation since it is impossible to see the orientation of the multi-lobular end 40a relative to multi-lobular opening 32a in the gear 32 when the shaft 40 is telescoped through the opening 39a of the cap 39. This also can lead to canting of the shaft when one of the lobular portions 40a contacts the fingers 42a of the springrip 42 causing the canting or non-coaxial introduction of shaft 40 into the aperture 39a in cap 39
The assembly and fastening of the caps 38 and 39 to the body 22 are expensive secondary operations that normally require either heat sealing or adhesive to maintain the caps in accurate assembled relation. Again, orientation of these elements during assembly introduces possible problems in orientation and rigidity in the assembly.
The problems enumerated above are eliminated by the teachings of the present invention which reduces the number of pieces used and the manner of assembly, thereby providing a new approach to solving the problems of manufacture in adjusting mechanisms as well as providing a superior more rigid structure that will insure proper orientation and mating of the gearset.
A secondary problem experienced by the prior art devices is the fact that when all of the gears are metallic in nature the cost of such gears is almost prohibitive in todays competitive marketplace. When all plastic gears are utilized it has been found that they do not have the necessary tooth shear strength to give adequate torque producing capabilities to overcome stuck headlamp frame assemblies that have been corroded by their environment. Where assemblies of plastic sleeve nuts, such as item 34a in Lisak '219, are assembled with adjustment gears 34 a further secondary operation expense is added to the entire adjustment mechanism.